Hydraulic regular system for fuel injection pumps

ABSTRACT

For the purpose of varying the extent of pressure response to r.p.m. changes in a hydraulic regulator system that controls the fuel delivery of a fuel injection pump, there is provided a pressure control valve and an arbitrarily variable throttle valve, both disposed in a conduit connecting the inlet and the outlet sides of a regulator pump of said system; said pressure control valve is gradually opened as the r.p.m.-dependent pressure increases; beyond a predetermined r.p.m., such opening is resisted by the pressure prevailing between said pressure control valve and said throttle valve.

United States Patent INJECTION PUMPS 3 Claims, 2 Drawing Figs.

[52] US. CL ..123/140I-G, 123/97 [51] Int. Cl F02d 1/00 [50] Field 01 Search 123/97, 98,

[56] References Cited UNITED STATES PATENTS 2,902,019 9/1959 Aldinger et al. l23/l39il3 2,995,898 8/l96l Thorner l23/l03 UX Primary ExaminerLaurence M. Goodridge Attorney-Edwin E. Greigg ABSTRACT: For the purpose of varying the extent ofpressure response to r.p.m. changes in a hydraulic regulator system that controls the fuel delivery of a fuel injection pump, there is provided a pressure control valve and an arbitrarily variable throttle valve, both disposed in a conduit connecting the inlet and the outlet sides of a regulator pump of said system; said pressure control valve is gradually opened as the r.p.m.-dependent pressure increases; beyond a predetermined r.p.m., such opening is resisted by the pressure prevailing between said pressure control valve and said throttle valve.

HYDRAULIC REGULAR SYSTEM FOR FUEL INJECTION I PUMPS BACKGROUN D OF THE INV ENTION This invention relates to a hydraulic regulator system for fuel injection pumps associated with internal combustion .engines and is of the type that includes a regulator pump, the delivery pressure of which affects a mechanism or setting member which controls the injected fuel quantities. The said delivery pressure is controlled by a pressure control valve disposed in a channel connecting the inlet and the outlet side of the regulator pump. The said pressure control valve includes a piston, the front face of which is exposed to the fuel pressure and is displaced by said pressure against the return force of spring means. The said pressure control valve is associated with a throttle valve in said channel.

In a known regulator system of the aforenoted type (such as disclosed in German Pat. No. 826,666), the mechanism determining the injected fuel quantities is formed by a hydraulic setting piston the front face of which is exposed to the delivery pressure and displaced against the force of a spring. During the course of such displacement, the piston actuates the fuel quantity control rod of the fuel injection pump. The delivery pressure of the regulator pump is maintained at a constant value by means of the pressure control valve. The pressure prevailing between the pressure control valve and the throttle valve formed in this structure as a regulator valve is controlled by the throttle valve as a function of the r.p.m., and exerts a force on the rear face of the setting piston, causing an r.p.m.- dependent displacement thereof. The throttle valve is formed as a plunger. the movements of which are dampened by an additional throttle.

OBJECT AND SUMMARY OF THE INVENTION It is an object of the invention to provide an improved hydraulic regulator of the aforeoutlined type whiehin order to obtain a good regulation, that is, to obtain rapidly a stable r.p.m. after a change either of the load or of the flow passage section of the throttlehas possibly small P-range (nonuniformity grade) and wherein, in contradistinction to known regulators, not only is a predetermined r.p.m. maintained at a stable value, but such r.p.m. may be arbitrarily varied.

Briefly stated, according to the invention, the throttle valve is arbitrarily variable (for example, by actuating the accelerator pedal) and the pressure control valve, as the r.p.m. increases, causes an increase in pressure, while the backface of the piston of the pressure control valve is exposed to the pressure prevailing between the pressure control valve and the throttle valve. In such an arrangement, the delivery pressure strongly increases for certain flow passage sections of the throttle valve even in case of small r.p.m. increments. Thus, the desired small P-range is obtained. In order to limit the pressure increase, there is provided a maximum pressure control valve arranged parallel with the pressure control valve and throttle valve.

The invention will be better understood, as well as further objects and advantages will become more apparent, from the ensuring detailed specification of a preferred, although exemplary, embodiment taken in conjunction with the draw in g.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a diagrammatic view of the preferred embodiment of the invention; and

FIG. 2 is a pressure-r.p.m. diagram including a plurality of regulator curves.

DESCRIPTION OF THE EM BODIM ENT Turning now to FIG. I, a regulator pump 1 delivers to a pressure conduit system 2 regulator liquid from a container 3. Said liquid exerts simultaneous pressure on a setting member 4, a pressure control valve 5 and a maximum pressure control valve 6. The setting member 4 comprises a piston 7 which is displaceable in a cylinder 8 by said pressure against the force of a return spring 9 and which, with its piston rod 10, actuates a device (not shown) for varying the fuel quantities delivered by the fuel injection pump (also not shown). The space 8a of the cylinder 8 which accommodates the return spring 9 communicates through a discharge channel 11 with the suction side of the regulator pump 1. The pressure prevailing in the conduit system 2 is regulated as a function of the r.p.m. by means of a pressure control valve 5 until a predetermined maximum pressure is reached, at which time the maximum pressure valve 6 opens.

The pressure control valve 5 includes a control piston 13 which, at its front face is exposed to the pressure of the admitted regulator liquid and is thus displaceable thereby against the force of a spring I4. Dependent upon the extent of its displacement, the control piston 13 opens a port [5 to a greater or lesser extent. The strength of response of the pressure in the conduit system 2 to increases of the r.p.m. depends upon the cross-sectional area of the piston 13, the configuration of the port 15 and the characteristics of the spring 14. The higher the r.p.m. the more liquid the regulator pump I delivers and the greater will be the displacement of piston I3 against the spring 14. It further follows that the higher the r.p.m., the greater the flow passage section of port 15. Thus, the pressure in the conduit system 2 increases with the increase of the r.p.m. Conversely, the pressure in the conduit system 2 decreases as the quantities delivered by the regulator pump I decrease. As the pressure increases, the fuel quantities delivered by he fuel injection pump are decreased by the setting member 4 until the r.p.m. adjusts itself to a corresponding value.

The port 15 communicates with an annular chamber I6 of the pressure control valve 5. Said chamber communicates through a port 17 with the space 26 accommodating spring 14. From the annular chamber I6 the regulator liquid flows to an arbitrarily variable throttle valve 19 through a conduit I8. From the throttle valve 19 the regulator liquid proceeds to a conduit system 20 which also receives liquid flowing through the maximum pressure valve 6. As the flow passage section of the throttle valve 19 is decreased, a pressure buildup is generated in the conduit I8 in the annular chamber 16, in bore 17 and in the space 26. This pressure affects the rear face 13b of piston I3 in the same direction as spring 14 and counteracts the pressure in the conduit system 2 affecting the front face 13a of the piston 13. As a result, the piston 13 is displaced towards the left, whereby the flow passage section of the port I5 is decreased. As a consequence, the pressure in the conduit system 2 increases. Since, as long as the pressure is below the maximum pressure, the entire liquid quantity delivered by the regulator pump I; is constrained to flow through the pressure control valve 5 and the throttle valve 19, the pressure changes which take place in the conduit system 2 and which are affected by the control pressure valve 5 and the throttle valve 19, are superimposed as seen in the diagram of FIG. 2.

In the diagram shown in FIG. 2, the ordinate represents the pressurep and the abscissa the r.p.m. n. The regulator curve I indicates the pressure increases in response to the r.p.m. increases as effected by the pressure control valve 5. Its course is, corresponding to the characteristics of spring 14, substantially linear and, dependent upon said spring characteristics, more or less steep. The throttle valve I9, on the other hand, causes a quadratic increase of pressure as the r.p.m. increases. Such a pressure increase is represented by the three curves II', II" and II' corresponding to three different flow passage sections of throttle valve I9. As soon as the pressure reaches the valve p the maximum pressure valve 6 opens (curve Ill). As seen from the diagram, up to a determined r.p.m. 11,, n or n that is, up to a determined liquid quantity delivered by the regulator pump I in a unit time), the pressure in the conduit system 2 is controlled substantially solely by the pressure control valve 5 according to the relatively gently and linearly rising curve I. Beyond said determined r.p.m. (set by the throttle valve 19), the control function of the throttle valve 19 becomes effective and thus, it contributes to the control of pressure in conduit system 2 according to one of the quadratic regulator cures ll, II" or 11" obtained by superposition.

1 Thus, as soon as the throttle valve 19 becomes effective in the pressure control, the pressure increases very rapidly as the r.p.m. increases. The result is a relatively large displacement of the setting member 4. Consequently, the change in the fuel quantities delivered by the fuel injection pump is also relatively large. Thus, the proportional range (nonuniformity grade) is now small and decreases further as the pressure increases.

The pressure in the conduit system 20 is controlled, as a function of the r.p.m., by means of a second pressure control valve 22 which operates similarly to the pressure control valve and which comprises a piston 27, a return spring 28 and a space 29 accommodating the spring 28. The level of the pressure in the pressure system 20, however, is maintained at a substantially lower value than that prevailing in the conduit system 2. The outlet conduit 23, and the space 29 communicate with the discharge channel ll. The conduit system includes a setting member 24 which operates similarly to the setting member 4 and which has a piston rod 25 connected in a known manner to an injection timer (not shown). The r.p.m.-dependent pressure prevailing in the conduit system 20 affects, across throttle valve 19, only very slightly the pressure in the conduit system 2, since the pressure in the conduit system 20 is maintained far below that prevailing in pressure system 2.

Turning once again to FIG. 2, the pressure-rpm. curve IV the conduit system 20 is substantially parallel with the curve I indicating identical spring characteristics. If, however, the characteristics of spring 29 in the pressure control valve 22 are difi'erent from those of the spring 14 in the pressure control valve 5, then the course of the curves l and IV would not be parallel.

What we claim is:

1. in a hydraulic regulator system associated with a fuel injection pump to determine the fuel quantities delivered thereby to an internal combustion engine s aidsystem is of the known type that includes (A) a regulator pump delivering regulator liquid under pressure, pressure actuates a setting member to control the delivery by said fuel injection pump, (B) a channel interconnecting the inlet and outlet sides of said regulator pump, (C) a pressure control valve disposed in said channel and regulating the delivery pressure of said regulator pump, said pressure control valve comprises a control piston having a front face exposed to said pressure and displaceable thereby against the force of return means, the improvements comprising,

A. an arbitrarily operable throttle valve disposed in said channel downstream of said pressure control valve and B. means admitting the pressure prevailing in said channel between said throttle valve and said pressure control valve to a rear face of said control piston to oppose the force exerted thereon by said delivery pressure.

2. An improvement as defined in claim 1, including a maximum pressure control valve connected to said channel parallel with said pressure control valve and said throttle valve.

3. An improvement as defined in claim 1, including an additional pressure control valve disposed in said channel downstream of said throttle valve, an additional setting member communicating with said channel and means admitting the pressure prevailing in said channel between said throttle valve and said additional pressure control valve to said additional setting member to affect the timing of fuel delivery. 

1. In a hydraulic regulator system associated with a fuel injection pump to determine the fuel quantities delivered thereby to an internal combustion engine, said system is of the known type that includes (A) a regulator pump delivering regulator liquid under pressure, said pressure actuates a setting member to control the delivery by said fuel injection pump, (B) a channel interconnecting the inlet and outlet sides of said regulator pump, (C) a pressure control valve disposed in said channel and regulating the delivery pressure of said Regulator pump, said pressure control valve comprises a control piston having a front face exposed to said pressure and displaceable thereby against the force of return means, the improvements comprising, A. an arbitrarily operable throttle valve disposed in said channel downstream of said pressure control valve and B. means admitting the pressure prevailing in said channel between said throttle valve and said pressure control valve to a rear face of said control piston to oppose the force exerted thereon by said delivery pressure.
 2. An improvement as defined in claim 1, including a maximum pressure control valve connected to said channel parallel with said pressure control valve and said throttle valve.
 3. An improvement as defined in claim 1, including an additional pressure control valve disposed in said channel downstream of said throttle valve, an additional setting member communicating with said channel and means admitting the pressure prevailing in said channel between said throttle valve and said additional pressure control valve to said additional setting member to affect the timing of fuel delivery. 